1. Field of the Invention
The present invention relates to a constant flow apparatus, and in particular relates to an improvement of the needle portion which undergoes a changing movement in response to the pressure of a fluid, and an improvement of the arrangeability for the fluid flow route in order to maintain the passing flow at a constant value.
2. Description of the Prior Art
In the water supply equipment of buildings such as hotels or the like for example, lavatories and showers are simultaneously used with ease at many locations. Now, because there is a concentrated demand for water supply, there is the problem that the water pressure becomes lowered, whereby the amount of water discharged by each water faucet is reduced. Further, as for the water supply equipment, the water supply pressure is set sufficiently high to ensure water supply to the end of the piping system. For this reason, in general when a water faucet is turned on, there is a tendency for water to gush out at an excessive discharge rate.
As a countermeasure in this regard, a constant flow apparatus has been proposed in which an appropriate amount of water is discharged at the output side without being affected by pressure changes of the input side. For example, Japanese Laid-Open Utility Model Application No. HEI 2-9906 discloses an apparatus in which an orifice is provided inside a tubular body, and a needle which is supported by a spring is arranged to face the orifice, wherein the needle position moves in response to the pressure of the fluid, whereby a constant flow operation that maintains the discharge amount at an appropriate value is carried out.
However, in the apparatus disclosed in Japanese Laid-Open Utility Model Application No. HEI 2-9906, it has been determined by experimental analysis that when there are pressure changes at the input side, it is easy for vibrations to arise in the needle, and there is the fear that such vibrations will increase and become unstoppable. Further, improvements have been sought due to fact that the vibrations of the needle generate noise and make discharging unstable.
As for the problems described above, it is inferred from experimental analysis that there is a relationship with the shape of the tip portion of the needle. Namely, in the published apparatus described above, from the fact that the tip portion of the needle is given a conical shape, the flow of the fluid will definitely form a laminar flow type state at the output side which passes the orifice. Such flow will flow while exhibiting a pulling force on the needle which is balanced by the elastic force of the spring. At this time, when there are pressure changes at the input side, the needle moves in response to such changing forces, but the needle moves too much because of the strong pulling force due to the flow at the output side discharged from the orifice. Accordingly, the spring exhibits a repulsive force which creates mutual interference, and for these reasons it is easy for vibrations to arise in the needle, and such vibrations can increase and become unstoppable.
On the other hand, with regard to a pipeline provided with a constant flow apparatus, there are many types with regard to thickness and diameter thereof, but in the meter system and the inch system for example, when there is only a small difference in the inside diameter, such items are roughly the same. However, even in such case, the prior art establishes the outside diameter of the constant flow apparatus to correspond to each pipeline, but when the mounting diameter does not match, the constant flow apparatus can not be made to function normally. For this reason, exclusive products for each of such pipelines need to be produced, and this creates the problem of high cost.
In view of the background described above, it is an object of the present invention to solve the problems described above by providing a constant flow apparatus which makes it possible to prevent abnormal excessive flows and noise by preventing vibration of the needle which carries out a constant flow operation to maintain the passing flow at a constant value, which carries out a discharge operation in a highly stable manner to maintain the passing flow at a constant value, and which makes it possible for mounting to be carried out in a proper state even when there is a slight difference with the pipeline diameter of the fluid flow route.
In order to achieve the object stated above, the constant flow apparatus according to the present invention is mounted in the flow route of a fluid to maintain the passing flow at a constant value, and is equipped with a tubular body which is fitted and mounted inside a pipeline forming the flow route, an orifice provided at the output end side of the tubular body, a movable needle arranged to face the orifice, and a spring which supports the needle positioned to face the orifice by an appropriate elastic force, wherein the tip portion of the needle is formed to have a flat surface.
Further, the constant flow apparatus is also equipped with an axial rod provided at the input end side of the tubular body, and a cylinder hole provided in the needle to receive the axial rod, wherein the fitting of the axial rod into the cylinder hole carries out a dampening operation which serves as a dampening means for dampening changing movement of the needle.
Further, the constant flow apparatus is also equipped with an annular sealing plate made from an elastic member such as rubber or the like mounted to an end face portion of the cylinder hole, wherein the inner edge of the annular sealing plate makes contact with the outer periphery of the axial rod fitted therein.
In the present invention, because the tip portion of the needle is formed to have a flat surface, after the flow passes through the gap with the orifice, drag is produced and a vortex is created, whereby the pulling force on the needle does not become very strong and remains weak, and a vibration process like that of the prior art is not reached.
Further, the constant flow apparatus preferably includes a tubular sealing member made from an elastic member such as rubber or the like provided on the outside of the tubular body to cover the tubular body, wherein a circumferential convex bulging portion is formed in the tubular sealing member. Further, a plurality of circumferential convex strip portions are preferably formed on the surface of the bulging portion of the tubular sealing member.
On the other hand, a plurality of vertical slits are preferably formed in the side periphery of the tubular sealing member along the axis thereof. In this case, a flow adjustment portion for adjusting the flow of the passing fluid is mounted to the tubular sealing member to cover the output end side of the tubular body, and the flow adjustment portion is provided with a plurality of slots or vertical slits which run along the axis.
Now, because the tubular sealing member formed from an elastic member such as rubber or the like has a circumferential convex bulging portion formed on the side periphery thereof, the bulging portion can be easily indented to make it possible for fitting to be carried out for pipeline inside diameters in the range from the diameter of the peak portion of the bulging portion when the peak portion is indented to a moderate degree to the diameter of the peak portion when it is almost completely indented.
Further, an outside flange portion is preferably provided at the input end side of the outside of the tubular body. In this way, for example, when the constant flow apparatus of the present invention is installed at a connecting portion of a pipeline which forms an existing water route so that the constant flow apparatus is inserted from both sides, the tubular body is inserted into the inside of the pipeline, and the outside flange portion is held between pipes on both sides. Accordingly, because the outside flange portion is the only exposed portion, the total length of the water route is not made that much longer.